Multijunction solar cell mesa isolation: Correlation between process, morphology and cell performance

Lafontaine, Mathieu de; Ayari, Farah; Pargon, E.; Gay, G.; Petit-Etienne, C.; Turala, Artur; Hamon, Gwénaëlle; Jaouad, Abdelatif; Volatier, M.; Fafard, S.; Aimez, Vincent; Darnon, Maxime

doi:10.1016/j.solmat.2022.111643

Cited by 4 publications

(5 citation statements)

References 17 publications

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“…This lower value can be explained by a higher saturation current, as observed in Figure 3b. The lower V oc relative to the standard cell can be attributed to higher surface recombination on the edges of each subcell introduced by the mesas etching steps and a higher surface/perimeter ratio [21]. The similar I-V characteristics confirm that the final MTMJSC device possesses comparable electronic properties to a reference cell when measured between the emitter of the top subcell and the base of the bottom subcell (see "complete cell" scheme in Figure 3a).…”

Section: I-v Measurementsmentioning

confidence: 76%

Multi-Terminal GaInP/GaInAs/Ge Solar Cells for Subcells Characterization

Bidaud,

Ayari,

Ferreol

et al. 2024

Energies

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Improvement of triple-junction (3J) III-V/Ge solar cells efficiency is hindered by the low current produced by the top and middle cells relative to the bottom cell (Ge). This can be explained by the difficulty of characterizing, on an individual basis, the subcells. We investigate the fabrication process of multi-terminal multi-junction solar cells (MTMJSC) and its potential as a promising architecture to independently characterize subcells of multi-junction solar cells. Here, we study monolithic triple-junction solar cells, with an InGaP top cell, an InGaAs middle cell and a Ge bottom cell interconnected by tunnel junctions. We demonstrate a fabrication process for MTMJSC on commercial wafers for characterization applications purposes. I-V measurements, under illumination, of two-terminals and MTMJSC were compared to validate that the MTMJSC fabrication process does not degrade the cells’ performance. The dark current of each subcell was also measured and an ideal-diode model used to determine the subcells electrical parameters. The results suggest a method to measure the relative absorption and the opto-electrical couplings between the subcells unambiguously, through EQE and electroluminescence measurements, based on basic micro-fabrication processes.

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Section: I-v Measurementsmentioning

confidence: 76%

Multi-Terminal GaInP/GaInAs/Ge Solar Cells for Subcells Characterization

Bidaud,

Ayari,

Ferreol

et al. 2024

Energies

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“…Front‐contacted solar cells (represented in Figure a) were fabricated via three levels using our own designed photolithographic mask. The main steps include the creation of a mesa structure down to the GaAs buffer [ 17 ] using low‐damage plasma etching (a similar design reported in ref. [18]) and electrode metal depositions.…”

Section: Methodsmentioning

confidence: 99%

High‐Efficiency GaAs Solar Cells Grown on Porous Germanium Substrate with PEELER Technology

Daniel,

Bidaud,

Chretien

et al. 2023

Solar RRL

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III‐V solar cells are mainly grown on GaAs or Ge substrate, which significantly contributes to the final cost and affects the sustainable use of these rare materials. We developed a so‐called PEELER process in which a porosification technique is used to create a weak layer between a Ge substrate and the epitaxial layers. This method enables the separation of the grown layers, allowing for the subsequent reuse of germanium and a reduction in the environmental and economic cost of optoelectronic devices. Technology validation using the device performance is important to assess the technology interest. For this purpose, we fabricated and compared the performance of 22 non‐detached single‐junction (s‐j) GaAs photovoltaic cells grown and manufactured on porosified 100mm Ge wafer without anti‐reflection coating (ARC). All the cells exhibit comparable performance to state‐of‐the‐art GaAs solar cells (grown or Ge or GaAs) with high efficiency (21.8% ± 0.78%) and thereby demonstrate the viability of growing high‐performance optoelectronic devices on detachable Ge films.This article is protected by copyright. All rights reserved.

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“…Compared to other isolation methods such as wet chemical etching or partial saw dicing, this process improves the Voc by 1 % for ~30 mm 2 solar cells. [15] When the P/A ratio increases, the optimized etch process keeps its superiority as illustrated figure 3a, with a Voc improvement of 10 mV compared to sub-optimal plasma etching process for a P/A of 40 cm -1 (1x1 mm 2 solar cell). Extrapolating the trend, we can anticipate a Voc of 2.365 V for 0.01 mm 2 solar cell (P/A of 400 cm -1 ) under one sun illumination.…”

Section: Mitigating Perimeter Effects In Sub-millimeter-scale Multiju...mentioning

confidence: 95%

“…More importantly, the width of the dicing line (kerf) is larger than 75 µm and damages the sidewall of devices. [15] This leads to a large waste of highvalue material when more dicing lines are required per wafer, i.e. when the dimension of the solar cells is reduced.…”

Section: Challenges Associated With Sub-millimeter-scale Multijunctio...mentioning

confidence: 99%

Sub-millimeter-scale multijunction solar cells for concentrator photovoltaics (CPV)

Darnon¹,

Lafontaine

Albert

et al. 2022

Physics, Simulation, and Photonic Engineering of Photovoltaic Devices XI

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Concentrator photovoltaic (CPV) technologies provide the highest photovoltaic conversion efficiency but remain too expensive for very large scale development. Reduction of the dimension (micro-CPV) is a promising approach towards cost reduction but necessitates sub-millimeter-scale high efficiency solar cells. In this paper, we review the challenges faced by sub-millimeter-scale solar cells for application in micro-CPV. We show that plasma etching processes are necessary to fabricate sub-millimeter-scale high-efficiency solar cells to avoid a waste of material in the isolation and dicing lines. We also show that despite the cell performance is known to degrade when the dimension of the cell is downscaled, this degradation can be negligible when optimized etching and passivation processes are used and when the cell operates under high concentration (>500x). The through-cell via contact architecture is a promising approach to avoid bus bars on the front side and therefore optimize the wafer usage and minimize dark current. Combining all these solutions, we claim that sub-millimeter-scale high efficiency solar cells as small as 0.01 mm 2 can be fabricated with more than 90% of wafer material used for photovoltaic conversion and without performance degradation when operating under 1,000x concentration compared to 1 mm 2 solar cells operating under 500x concentration. Challenges on characterization and in-line metrology remain to be solved and manufacturing lines need now to be adapted to provide commercial solutions for micro-CPV.

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Multijunction solar cell mesa isolation: Correlation between process, morphology and cell performance

Cited by 4 publications

References 17 publications

Multi-Terminal GaInP/GaInAs/Ge Solar Cells for Subcells Characterization

Multi-Terminal GaInP/GaInAs/Ge Solar Cells for Subcells Characterization

High‐Efficiency GaAs Solar Cells Grown on Porous Germanium Substrate with PEELER Technology

Sub-millimeter-scale multijunction solar cells for concentrator photovoltaics (CPV)

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